(WOMENSENEWS)–The latest reports casting doubt on the value of mammography for fighting breast cancer have added fuel to an intense controversy, leaving women with little certainty and much confusion.
However, many leading advocates say the recent studies questioning the expensive and uncomfortable test millions of women endure each year is long overdue–and now is the time to develop new approaches to detecting and treating the disease.
The controversy erupted after news reports in January said that independent scientific advisers to the National Cancer Institute had reviewed seven major mammography studies and found five of them to be so flawed as to be useless. Because the remaining two studies presented conflicting results, the panel was not convinced that mammography prevents death from breast cancer. The panel’s findings confirmed the results of a similar study in the British medical journal, The Lancet. Yet other researchers have looked at the same studies and evaluated them differently, discounting research that the National Cancer Institute panel praised and praising studies it rejected.
Debate was reignited Thursday when 10 medical organizations, including the American Cancer Society, released an open letter to women stating that "lives will be lost" if women are discouraged from getting mammograms, and urging them "to continue to follow the advice of their physicians."
The letter came four days after the New York Times editorial page expressed concern that the medical establishment would ignore the challenges to the current medical practice.
Though the questioning of mammography is jarring for women, activists say it presents an opportunity to focus research efforts on prevention, and on new, more accurate, ways to detect and treat breast cancer.
"My response was, ‘It’s about time this evidence starts being discussed,’" said Barbara Brenner, executive director of Breast Cancer Action in San Francisco, an outspoken group of people affected by breast cancer. "Activists involved in breast cancer have understood for a long time the limitations of mammography," she added. "Some people say, ‘Oh, this is going to confuse women.’ Women aren’t stupid."
Susan Love Says Tests Need to be More Precise
In use since the late 1960s, mammography involves clamping a woman’s breast between two plates in a special x-ray machine, applying low doses of radiation and taking pictures of the soft tissue. A radiologist analyzes the film, searching for distortions, densities, masses or deposits. A second type of breast x-ray, a diagnostic mammogram, is used for further evaluation of a patient following the discovery of a lump or other suspicious finding.
Screening mammography has many limits. For one thing, it does not prevent cancer. "By the time you can feel a cancer or see it on a mammogram, it’s been there 8 to 10 years," said Dr. Susan Love, a breast cancer expert and author. By contrast, the Pap smear allows testing of pre-cancerous cervical cells to see if they present abnormalities that might develop into cervical cancer. Since its introduction, the Pap smear has resulted in a dramatic reduction in deaths.
In addition, women’s breasts differ enormously and dense fat or tissue can inhibit a clear x-ray. Sometimes tumors are missed; other times, abnormal findings are reported in women who, some nerve-wracking months later, are found to be free of cancer. Experts note the success of breast screening also depends on the quality of the facilities and the personnel.
"Before I was diagnosed with breast cancer, I thought, if I got a yearly mammogram, I would be okay. I saw ads that said you have a 98 percent chance of being cured if you have yearly mammograms. That was lying. People put too much faith in this," said Helen Schiff, a medical activist in New York City, first diagnosed with noninvasive breast cancer in 1989.
Medical understanding about the nature of breast cancer has changed since screening mammograms first began, said Schiff, who attends medical conferences throughout the country.
The original premise of early detection was that a cluster of cancer cells would start as a small tumor, grow, and then spread to other parts of the body, becoming deadly. Newer findings indicate size may not be the distinctive factor. "Sometimes a small cancer can be very aggressive and already have spread, and other times, a big cancer is not doing anything," said Dr. Love.
Approximately one-third of women diagnosed with breast cancer have cells that will respond well to established treatments. "The earlier we find it, the more likely it is she will respond well, and, if not treated, she will die," said Brenner. Her organization currently recommends mammograms for women over 50, but is reviewing the policy.
Conversely, another third of women diagnosed have abnormal cells that are actually causing no harm. One common form is DCIS, or ductal carcinoma in situ. Women with DCIS are sometimes over-treated with unnecessary radiation or mastectomy, say advocates, when monitoring would be better.
MaryAnn Napoli, associate director of the Center for Medical Consumers in New York City, said that 40,000 women are treated, often unnecessarily, for DCIS each year. She called it a problem so severe that a moratorium on screening mammography should be called until DCIS is better understood.
The real concern is that mammography can do little to distinguish between cancerous cells that are life-threatening and those that will cause no harm and can be left alone. Biomarkers that might point to especially aggressive cancers are only now being developed. DNA arrays, for example, are finding different types of breast cancer with varying recurrence rates, based on cell characteristics, not size.
"We’re going from a crude way of trying to predict and getting better at honing in," said Dr. Love.
Safer, More Effective Screening Tools May Already Exist
The well-recognized limitations of mammography have led to investigations into other methods for screening and detection of breast cancer. A committee of 15 health professionals and an advocate assembled by the Institute of Medicine, a division of the National Academies, reviewed technologies for the early detection of breast cancer in 2001. Its published report, "Mammography and Beyond," reviews more than 20 imaging technologies and a dozen biological methods that might be used in early detection.
Several technologies have already been approved by the Food and Drug Administration, including ultrasound, magnetic resonance imaging (MRI), computer-aided detection and diagnosis and thermography. Brenner said she is particularly hopeful about thermography because it relies upon heat, not radiation, which carries a cancer risk itself.
Ultrasound uses sound waves to create breast images and, unlike mammography, can differentiate between water-filled cysts and other solid lesions that might be cancerous. Digital mammography inputs breast images into a computer, like a digital camera, so that an investigator can magnify certain portions for a closer look. With computer-aided detection, a regular mammogram can be fed into a computer, which can scan and search for imperfections as an aid to a radiologist. Scintimammography involves injecting a woman with a radioactive compound that is attracted to cancer cells and shows up on a scanning machine.
Other technologies work by tapping into genetic and biochemical advances to search for "markers" in cancer cells, for example, by identifying specific genes that place women at high risk. Some scientists envision a blood test, similar to the test now in use for detecting prostate cancer. Most of these methods will take years to develop, however.
Dr. Love and a company that she founded have pioneered a method called ductal lavage, which is currently being tested as a tool for assessment of high-risk women. Based on findings that breast cancer begins with abnormal cells in the lining of the milk ducts, the procedure involves first drawing fluid with mild suction, and then threading a hair-thin catheter through the nipple into any ducts that produced fluid. The cells are then analyzed in a lab for abnormalities.
Dr. Love hopes researchers can use the technique to advance knowledge about cancer, such as studying estrogen in the breast or pesticide accumulation.
"We need to get down to where we can find cells that are thinking about being cancer," she said.
The Institute of Medicine committee listed 11 characteristics to the "ideal" screening tool, including low risk of harm, high degrees of specificity, noninvasive, cost-effective, ability to distinguish life-threatening lesions from those that are less likely to progress. This ideal "has not yet been developed," the committee concluded.
Meanwhile, Brenner and other activists hope the current debate will shift the public’s focus to the primary concern: finding means of preventing the 180,000 cases of breast cancer each year and finding treatments to roll back the annual toll of 40,000 deaths.
"We do need screening technologies that are more effective," said Brenner. "But at the end of the day, none of it is going matter until we have better treatments."
Cynthia L. Cooper is an independent journalist in New York.
For more information:
National Breast Cancer Coalition
Search on ‘Mammography’
"The Mammography Screening Controversy:Preliminary Questions and Answers,"
February 1, 2001: